Rocket-maker United Launch Alliance is putting in motion efforts to modify its Atlas 5 rocket pad at Cape Canaveral into a human launch site capable of loading astronaut crews in commercial spacecraft of the future.

An Atlas 5 with one strap-on booster is slated to carry the Boeing capsules. Credit: Ben Cooper/Spaceflight Now

The firm announced this week it has hired Hensel Phelps Construction Co. of Orlando, which built the site a dozen years ago, to manage the upcoming project.

"Hensel Phelps brings significant experience working major construction projects including the original construction for Atlas 5 at SLC-41, as well as Atlas modifications at SLC-3 in California," said George Sowers, ULA vice president of Human Launch Services. "We are honored that The Boeing Company with its Crew Space Transportation (CST)-100 spacecraft has selected our flight-proven Atlas 5 launch vehicle and will be our partners as we move into this next phase of development."

Hensel Phelps will partner with ULA, officials said, to design the crew accommodation tower and access arm needed for astronauts at Complex 41 to board their spacecraft.

What's more, an emergency egress system will be created to provide astronauts and pad workers a way to rapidly evacuate the area in the event of a dangerous situation.

The deal also includes developing the overall project requirements, cost and schedule projections, and risk mitigation for modifying to the existing launch facilities for commercial crew operations in a 21-month program.

"Hensel Phelps is excited about teaming with ULA and their partners on the modifications of SLC-41," said Kirk Hazen, vice president of Hensel Phelps. "It is an honor and privilege to be a part of the next generation of human spaceflight."

The CST-100 capsule approaches the space station for docking. Credit: Boeing

The Atlas 5 rocket family has been flying since August 2002, carrying out 33 successful missions from both coasts combined, including 10 flights dedicated to the Defense Department, 9 commercial missions with communications spacecraft, seven for NASA and seven with spy satellites for the National Reconnaissance Office.

The Cape vehicles are assembled inside the 293-foot tall Vertical Integration Facility located 1,800 feet from the pad, then wheeled out aboard a mobile launching platform the day before flight.

The 1.4-million pound mobile platform is what the Atlas 5 sits upon from the time it is stacked together until the main engine is fired at liftoff. Umbilicals feeding fuel, power and all other lines from the ground to the rocket run through the platform and its towering mast.

But the concept of Atlas 5 is meant to spend very limited time on the pad, which does not feature a service gantry or permanent umbilical tower like other sites. That makes creation of the commercial crew structures a critical step in launching humans instead of only satellite payloads.

Work to build Complex 41 began in 1963 and the pad opened for business in 1965, hosting 27 Titan rocket launches through 1999 that sent NASA's Viking landers to Mars, the twin Voyager probes to the solar system's outer planets and various other communications and military satellites into Earth orbit.

In October 1999, amid much fanfare, the Titan's mobile service tower and umbilical tower were explosively toppled to the ground, allowing workers to safely dismantle the structures that Atlas 5 would not need given the "clean pad" concept.

An artist's concept of the Atlas 5 rocket with a CST-100 capsule rolls to the Complex 41 launch pad. Credit: Boeing

The most visible parts of the pad -- all left over from the Titan program -- are the four lightning protection masts, designed to shield the rocket during Florida's frequent thunderstorms, and the massive flame duct.

There are also four fuel tanks scattered around the pad. The largest is the sphere-shaped 465,000 gallon liquid oxygen tank that holds the super-cold cryogenic for the Atlas first stage. Two 48,000 gallon RP-1 tanks are filled with the highly-refined kerosene fuel, also for the Atlas booster. The Centaur upper stage consumes liquid oxygen and liquid hydrogen, which are stored in separate 28,000 gallon and 48,000 gallon tanks, respectively.

"With 33 successful missions spanning a decade of operational service, the commercially developed Atlas 5 is uniquely qualified to provide launch services for the Crew Transportation System," said Sowers. "We look forward to working with Hensel Phelps to take the next steps in launching crew from SLC-41 and providing safe and reliable crew launch services as early as 2015."

Atlas 5 is the rocket of choice for Boeing's CST-100 capsule and Sierra Nevada's Dream Chaser vehicle in NASA's Commercial Crew Integrated Capability (CCiCap) program to launch astronauts from U.S. soil into low-Earth orbit, ending the gap in human spaceflight after retirement of the space shuttles.